1. Field of the Invention
The present invention relates to a permanent magnet rotating electrical machine provided with a rotor having permanent magnets and a stator, and a permanent magnet rotating electrical machine system using the same.
2. Related Art
An induction motor has been employed as a rotating electrical machine to be used for an electric locomotive or vehicle. In recent years, however, low cost of permanent magnets and high performance of semiconductor devices are raising the trend of employing a permanent magnet rotating electrical machine driven by a power conversion system.
In this situation, in order to improve the electrical characteristics of a rotating electrical machine, various types of permanent magnetic rotor structures are considered. For the rotor of a permanent magnet rotating electrical machine disclosed in Japanese Patent Laid-Open Application No. 2003-116235, divided permanent magnet segments are disposed, and flux barriers are arranged behind the divided permanent magnet segments, thereby reducing leakage fluxes to the inside of the rotor to increase the number of flux linkages with the coils of a stator.
[Problem to be Solved]
As the capacities of rotating electrical machines are getting larger, consideration of the mechanical strength of a rotor, which is not a problem for a small-sized machine with a small rotor diameter, is becoming important. Particularly, permanent magnets are often attached to the surface of a rotor core with adhesive, and tend to be peeled off by movement in the radial direction due to a centrifugal force. On the other hand, in order to avoid peeling off of permanent magnets, if plural holes are formed along the axial direction in a circumferential region of a rotor core and permanent magnets are arranged in the holes, the distance between the surface of a permanent magnet and a stator magnetic pole is increased to cause a problem of a drop in magnetic properties. Therefore, it is necessary to achieve both a sufficient mechanical strength of a rotor and magnetic properties.
In this situation, an object of the invention is to provide a permanent magnet rotating electrical machine capable of restricting the movement of permanent magnets due to centrifugal force, and a permanent magnet rotating electrical machine system using the same.